Spinal correction tensioning system

ABSTRACT

A vertebral column correction system for correcting a spinal deformity without fusing the joint segments is disclosed. The vertebral column correction system may have first and second vertebral anchors secured to first and second vertebrae. The vertebral column correction system may further comprise one or more intermediate vertebral anchors secured to vertebrae between the first and second vertebrae. A connection member may be disposed within a head portion of the vertebral anchors. At least a portion of the connection member may be a flexible member, such as a flexible cord, configured for tensioning between at least two vertebral anchors for providing a desired amount of tension to apply a correctional force to the spinal column. A spring member, or other tensioning member, may maintain the tension of the connection member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/490,845, filed Jun. 24, 2009, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The disclosure is directed to a system, apparatus and method forproviding stabilization to one or more vertebrae of a spinal column.More particularly, the disclosure is directed to a system, apparatus andmethod for correcting a spinal deformity.

BACKGROUND

The spinal column is a highly complex system of bones and connectivetissues that provides support for the body and protects the delicatespinal cord and nerves. The spinal column includes a series of vertebraestacked one on top of the other, each vertebra includes a vertebral bodyincluding an inner or central portion of relatively weak cancellous boneand an outer portion of relatively strong cortical bone. Anintervertebral disc is situated between each vertebral body to cushionand dampen compressive forces experienced by the spinal column. Avertebral canal, called the foramen, containing the spinal cord andnerves is located posterior to the vertebral bodies. In spite of thecomplexities, the spine is a highly flexible structure, capable of ahigh degree of curvature and twist in nearly every direction. Forexample, the kinematics of the spine normally includes flexion,extension, rotation and lateral bending.

There are many types of spinal column disorders including scoliosis(abnormal curvature and twisting of the spine), kyphosis (abnormalforward curvature of the spine, usually in the thoracic spine), excesslordosis (abnormal backward curvature of the spine, usually in thelumbar spine), spondylolisthesis (forward displacement of one vertebraover another, usually in a lumbar or cervical spine) and other disorderscaused by abnormalities, disease, or trauma, such as ruptured or slippeddiscs, degenerative disc disease, fractured vertebra, and the like.Patients that suffer from such conditions usually experience extreme anddebilitating pain as well as diminished range of motion and nervefunction. These spinal disorders may also threaten the critical elementsof the nervous system housed within the spinal column.

There is an ongoing need to provide alternative systems, apparatuses,and methods of correcting deformities of the spinal column.

SUMMARY

The disclosure is directed to several alternative systems, apparatusesand methods of correcting a spinal deformity.

Accordingly, one illustrative embodiment is a vertebral columncorrection system including a first vertebral anchor configured to besecured to a first vertebra and a second vertebral anchor configured tobe secured to a second vertebra. The vertebral column correction systemmay further include one or more intermediate vertebral anchors, eachconfigured to be secured to an intermediate vertebra located between thefirst vertebra and the second vertebra. The vertebral anchors may eachhave a head portion. A connection member may be configured to extendthrough the head portion of the first vertebral anchor, through the headportion of each of the one or more intermediate vertebral anchors, andthrough the head portion of the second vertebral anchor. At least aportion of the connection member may be a flexible member configured fortensioning between at least two vertebral anchors. The connection membermay be sized for location within the head portion of each of the one ormore intermediate vertebral anchors and may be sized to belongitudinally displaceable through the head portion of at least one ofthe one or more intermediate vertebral anchors. The vertebral columncorrection system may be free of structure that constrains thedisplacement of the head portion of the first vertebral anchor towardthe head portion of each of the one or more intermediate vertebralanchors.

Another illustrative embodiment is a vertebral column correction systemincluding a first vertebral anchor and a second vertebral anchorconfigured to be secured to a first vertebra and a second vertebra,respectively. The vertebral column correction system may furthercomprise one or more intermediate vertebral anchors, each configured tobe secured to an intermediate vertebra located between the firstvertebra and the second vertebra. The vertebral anchors may eachcomprise a head portion. A connection member may be configured to extendthrough the head portion of the first vertebral anchor, through the headportion of each of the one or more intermediate vertebral anchors, andthrough the head portion of the second vertebral anchor. At least aportion of the connection member may be a flexible member configured fortensioning between at least two vertebral anchors. The vertebral columncorrection system may further comprise a tensioning member configured tobe coupled to a first end of the connection member and positionable on aside of the head portion of the first vertebral anchor away from the oneor more intermediate vertebral anchors and the second vertebral anchor.The tensioning member may be configured to hold the connection member intension between the first vertebral anchor and the second vertebralanchor.

Yet another illustrative embodiment is a method of correcting a spinaldeformity. The method includes securing a first vertebral anchor to afirst vertebra, securing a second vertebral anchor to a second vertebra,and securing one or more intermediate vertebral anchors to one or moreintermediate vertebra located between the first vertebra and the secondvertebra. Each of the vertebral anchors may include a head portion. Aconnection member may be captured within the head portions of each ofthe one or more intermediate vertebral anchors while maintaininglongitudinal movement of the connection member through the head portionsof at least one of the one or more intermediate vertebral anchors. Atensioning member may be coupled to a first end of the connectionmember. The tensioning member may be positioned on a side of the headportion of the first vertebral anchor away from the one or moreintermediate vertebral anchors and the second vertebral anchor. A secondend of the connection member may be secured to the head portion of thesecond vertebral anchor. The connection member may be tensioned to adesired amount of tension.

The above summary of some example embodiments is not intended todescribe each disclosed embodiment or every implementation of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a perspective view of an illustrative vertebral columncorrection system installed along a portion of a spinal column;

FIG. 2 is a perspective view illustrating the first end portion of theillustrative vertebral column correction system of FIG. 1;

FIGS. 3A-3D are alternative embodiments of illustrative vertebralanchors which may be used with the vertebral column correction system ofFIG. 1;

FIGS. 4-7 illustrate one mode of installation of the vertebral columncorrection system of FIG. 1; and

FIG. 8 is an alternative embodiment of an illustrative vertebral columncorrection system installed along a portion of a spinal column undertension.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit aspects of the invention tothe particular embodiments described. On the contrary, the intention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the invention. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

Now referring to the drawings, FIG. 1 is a perspective view of anillustrative vertebral column correction system 10. The vertebral columncorrection system 10 may be used to correct spinal deformities, such asscoliosis, kyphosis, or other deformities with or without fusing one ormore joint segments. The vertebral column correction system 10 may havea first end portion 11 and a second end portion 13. In some embodiments,the vertebral column correction system 10 may comprise a first vertebralanchor 12 having a first side surface 14 and a second side surface 16secured to a first vertebra 18. The vertebral column correction system10 may further comprise a second vertebral anchor 20 having a first sidesurface 22 and a second side surface 24 secured to a second vertebra 26.The second vertebra 26 may be adjacent to the first vertebra 18 or maybe spaced one, two, three, four, or more vertebrae from the firstvertebra 18. The vertebral column correction system 10 may furthercomprise one or more intermediate vertebral anchors 28 disposed betweenthe first and second vertebral anchors 12, 20. Each of the one or moreintermediate vertebral anchors 28 may be secured to one or more vertebra30 between the first and second vertebrae 18, 26. Each of the vertebralanchors 12, 20, 28 may comprise a head portion and a shank portion, someexamples of which will be discussed in more detail with respect to FIGS.3A-3D.

The vertebral column correction system 10 may further comprise aconnection member 32, such as a flexible cord, or other flexible member,extending through the head portion of the first vertebral anchor 12towards the second vertebral anchor 20. In some embodiments, theconnection member 32 may vary in flexibility and elongation propertiesalong the length L of the connection member 32. For example, a portionof the connection member 32 may be significantly more rigid if greatercorrection of a spinal deformity is needed at particular levels of thespine and less rigid in levels of the spine requiring less correction.

The connection member 32 may be held in tension between the first andsecond vertebral anchors 12, 20. In some embodiments, the vertebralcolumn correction system 10 may further comprise a tensioning member 34,such as a spring member 35, to provide tension to the connection member32 and potential elongation of the connection member 32. In someembodiments, the tensioning member 34 may be loaded in compression inorder to apply tension to the connection member 32. For example, thetensioning member 34 may be a helical spring or a polymeric spacer, suchas a polycarbonate urethane (PCU) spacer, for example, which may beloaded in compression. The tensioning member 34 may be disposed over theconnection member 32 and between the first side surface 14 of the firstvertebral anchor 12 and a ferrule flange 36. The tensioning member 34,shown as a spring member 35, may have a first end 38 adjacent to theferrule flange 36 and a second end 40 adjacent to the first side surface14 of the first vertebral anchor 12. The ferrule flange 36 may beattached to a first end 42 of the connection member 32 such that theconnection member 32 extends through the tensioning member 34 (e.g., thespring member 35). For instance, the ferrule flange 36 may be crimped,clamped, or otherwise secured to the first end 42.

The vertebral column correction system 10 may be free of any structurethat constrains the displacement of the head portion of the firstvertebral anchor 12 towards the head portion of each of the intermediatevertebral anchors 28. Similarly, the vertebral column correction system10 may be free of any structure that constrains the displacement of thehead portion of the second vertebral anchor 20 towards the head portionof each of the intermediate vertebral anchors 28. In some embodiments,the vertebral column correction system 10 may also be free of anystructure that constrains the displacement of the head portion of theintermediate vertebral anchors 28 toward one another. For instance, thevertebral column correction system 10 may not include spacers or otherstructure disposed around the connection member 32 between the headportion of adjacent vertebral anchors 12, 20, 28.

Turning now to FIG. 2, which illustrates a perspective view of the firstend portion 11 of the illustrative vertebral column correction system10, the tensioning member 34, connection member 32, and ferrule flange36 will be discussed in more detail. The connection member 32 may have afirst end 42 and a second end 44 (see FIG. 1). While the connectionmember 32 is shown having a circular cross-section, the connectionmember 32 may have any cross-section desired such as, but not limitedto, square, rectangle, polygonal, or elliptical. In one embodiment, theconnection member 32 may be formed from polyethylene-terephthalate(PET), although it will be recognized that various other materialssuitable for implantation within the human body and for providingstabilization of the spine while maintaining flexibility may be used. Inother embodiments, the connection member 32 can be constructed of otherflexible materials such as metal, polymeric materials, or combinationsof flexible materials. The connection member 32 may be of any lengthnecessary to extend between two, three, four, or more vertebrae of thespinal column.

A ferrule flange 36 may be fixedly attached to a first end 42 of theconnection member 32. The ferrule flange 36 may be attached adhesively,mechanically (e.g. clamped or crimped), or by any other method known inthe art. In some instances, the tensioning member 34 may be placed overthe flexible cord 32 by sliding the tensioning member 34 over the secondend 44 of the cord 32 and advancing the tensioning member 34 towards theferrule flange 36, attached to the first end 42 of the connection member32, such that the connection member 32 extends through the tensioningmember 34. In some embodiments, the vertebral column correction system10 may further include a flange (not explicitly shown) disposed betweenthe tensioning member 34 and the first side surface 14 of the firstvertebral anchor 12.

The tensioning member 34 (e.g., the spring member 35) may allow theconnection member 32 to be placed under various amounts of tensiondepending on the amount of compression placed on the tensioning member34 (e.g., the spring member 35). In some embodiments, the spring member35, or other tensioning member, may allow the vertebral columncorrection system 10 to be tensioned and allow movement in alldirections while providing tension to the connection member 32. Thespring member 35, or other tensioning member, may also allow tension andtravel to be customized by a surgeon to provide the intended spinalcorrection by controlling the compression of the spring member 35, orother tensioning member, and/or adjusting the compression of the springmember 35, or other tensioning member, intra-operatively and/orpost-operatively.

In some embodiments, the ferrule flange 36 may prevent the tensioningmember 34 from advancing past the first end 42 of the connection member32. Once the tensioning member 34 is in place, the second end 44 of theconnection member 32 may be advanced longitudinally through the headportion of the vertebral anchors 12, 20, 28, beginning with the firstvertebral anchor 12, continuing with the intermediate vertebralanchor(s) 28, then the second vertebral anchor 20. Thus, the connectionmember 32 may be advanced through the head portion of each intermediatevertebral anchor 28 prior to being advanced through the head of thesecond vertebral anchor 20. In embodiments in which the vertebralanchors are top loading pedicle screws, the system 10 may be positionedin the head portions in another order if desired. For instance, inembodiments in which at least the intermediate vertebral anchors 28 aretop-loaded pedicle screws, the connection member 32 may be advancedthrough the intermediate vertebral anchors 28 prior to or subsequent topositioning the connection member 32 in the head portions of the firstand/or second vertebral anchors 12, 20.

FIGS. 3A-3D illustrate alternative embodiments of an illustrativevertebral anchor which may be used with the vertebral column correctionsystem 10. FIG. 3A illustrates a vertebral anchor 112 having a headportion 114 and a shank portion 116. While the shank portion 116 isshown as a threaded shank, it is contemplated that the vertebral anchor112 may comprise other devices for securing to a vertebra (e.g.vertebral hooks). In some embodiments, the head portion 114 may have agenerally circular cross-sectional shape. In other embodiments, the headportion 114 may comprise a cross-sectional shape other than circularsuch as, but not limited to, generally square, rectangular, polygonal,and elliptical. The head portion 114 may further include a channel, suchas a through hole or bore 118, extending from a first side surface 120to a second side surface 122 for receiving the connection member 32. Thethrough hole 118 or other channel may be sized and shaped to accommodatethe connection member 32. In some embodiments, the through hole 118 mayhave a diameter that is substantially the same as an outer diameter ofthe connection member 32. In other embodiments, the through hole 118 mayhave a diameter that is slightly larger or substantially larger than thediameter of the connection member 32. The head portion 114 may furtherinclude an opening, such as a bore 124, extending from a top surface 126of the head portion 114 to the through hole 118. The bore 124 maycomprise a threaded region (not explicitly shown) for receiving a setscrew 128 or other locking means. In some embodiments, the set screw 128may threadably engage the head portion 114 and secure the connectionmember 32 within the through hole 118. In other embodiments, theconnection member 32 may pass through the through hole 118 to capturethe connection member 32 in the head portion 114, but may not be securedwithin the through hole 118 or other channel.

FIG. 3B illustrates an exploded view of another illustrative vertebralanchor 212 having a head portion 214 and a shank portion 216. While theshank portion 216 is shown as a threaded shank, it is contemplated thatthe vertebral anchor 212 may comprise other devices for securing to avertebra (e.g. vertebral hooks). The head portion 214 may be generallyU-shaped forming a generally concave channel 218 extending from a firstside surface 232 to a second side surface. While the channel 218 isshown as generally concave, it is contemplated that the channel 218 maybe shaped to conform to the connection member 32. The vertebral anchor212 may further comprise a locking member 220. The locking member 220may comprise a generally convex portion 222 configured to mate with theconnection member 32. While the locking member 220 is shown as having agenerally convex portion 222, it is contemplated that the portion 222may be shaped to generally coincide with the shape of the connectionmember 32. The locking member 220 may further comprise a bore 224extending from a top surface 230 towards the generally convex portion222. The bore 224 may be configured to receive a set screw 228 or otherlocking means. The head portion 214 of the vertebral anchor 212 mayfurther comprise a threaded region 226 for receiving the set screw 228.When the vertebral anchor 214 is assembled the connection member 32 maybe disposed between the channel 218 and the generally convex portion 222of the locking member 220. The locking member 220 may be held within thehead portion 214 of the vertebral anchor 212 by the set screw 228 thuscapturing the connection member 32 in the head portion 214. In someembodiments, the set screw 228 may retain the locking member 220 withinthe head portion 214 of the vertebral anchor 212 without applying aclamping force onto the connection member 32 thus providing a channelwhich captures the connection member 32 yet allows longitudinal movementof the connection member 32 therethrough. In other embodiments, the setscrew 228 may secure the locking member 220 tightly against theconnection member 32 such that the connection member 32 is fixedly heldwithin the head portion 214 of the vertebral anchor 212.

FIG. 3C illustrates an exploded view of another illustrative vertebralanchor 312 having a head portion 314 and a shank portion 316. While theshank portion 316 is shown as a threaded shank, it is contemplated thatthe vertebral anchor 312 may comprise other devices for securing to avertebra (e.g. vertebral hooks). The head portion 314 may be generallyU-shaped forming a generally concave channel 318. While the channel 318is shown as generally concave, it is contemplated that the channel 318may be shaped to conform to the connection member 32. The vertebralanchor 312 may further comprise a locking member 320. The locking member320 may comprise a generally convex portion 322 configured to mate withthe connection member 32. While the locking member 320 is shown ashaving a generally convex portion 322, it is contemplated that theportion 322 may be shaped to generally coincide with the shape of theconnection member 32. The locking member 320 may further comprise achannel 324 extending down a first side 332 and an opposite second side(not explicitly shown) of the locking member 320. The channel 324 may beconfigured to receive an engaging member 326 or other locking means. Theengaging member 326 may further comprise two flared portions 334configured to mate with holes 330 in the head portion 314 of thevertebral anchor 312.

The head portion 314 of the vertebral anchor 312 may further comprise aslot 328 disposed within the interior portion 338, 340 of the headportion 314 for receiving the engaging member 326. In some embodiments,the slot 328 may be sized such that the engaging member 326 may be undercompression while it is disposed within the slot 328. In otherembodiments, the slot 328 may be sized such that the engaging member 326freely slides within the slot 328. The head portion 314 may furthercomprise a first hole 330, extending from a side portion 336 orthogonalto the channel 318 and into the channel 318. The head portion 314 maycomprise a second hole (not explicitly shown) positioned opposite thefirst hole 330 and extending through a second side portion 344 into thechannel 318. The connection member 32 may be placed within the channel318 prior to assembling the vertebral anchor 312 and the locking member320. Once the connection member 32 is disposed within the channel 318,the locking member 320 may be placed within the head portion 314 of thevertebral anchor 312. When assembled, the channel 324 of the lockingmember 320 may coincide with the channel 328 of the head portion 314.The locking member 320 may further comprise flared regions 342configured to prevent the locking member 320 from being longitudinallydisplaced from the head portion 314. Once the locking member 320 isdisposed within the head portion 314, the engaging member 326 may beadvanced through the channels 324, 328 until the flared portions 334engage the holes 330. When the flared portions 334 engage the holes 330,the locking member 320 may be secured within the head portion 314. Whenthe vertebral anchor 312 is assembled the connection member 32 may bedisposed between the channel 318 and the generally convex portion 322 ofthe locking member 320. The locking member 320 may be held within thehead portion 314 of the vertebral anchor 312 by the engaging member 326thus capturing the connection member 32 in the head portion 314. In someembodiments, the engaging member 326 may retain the locking member 320within in the head portion 314 of the vertebral anchor 312 withoutapplying a clamping force onto the connection member 32, thus providinga channel which captures the connection member 32. In other embodiments,the engaging member 326 may secure the locking member 320 tightlyagainst the connection member 32 such that the connection member 32 isfixedly held within the head portion 314 of the vertebral anchor 312.

FIG. 3D illustrates an exploded view of another illustrative vertebralanchor 500 having a head portion 502 and a shank portion 504. While theshank portion 504 is shown as a threaded shank, it is contemplated thatthe vertebral anchor 500 may comprise other devices for securing to avertebra (e.g., vertebral hooks). The head portion 502 may be generallyU-shaped having a first arm 506 and a second arm 508 extending from abase portion of the head portion 502, defining a generally U-shapedconcave channel 510 therebetween extending from one side of the headportion 502 to an opposite side of the head portion 502. While thechannel 510 is shown as being generally concave, it is contemplated thatthe channel 510 may be shaped to conform to the connection member 32.

The vertebral anchor 500 may further include a securing member, such asa threaded set screw 530. The set screw 530 may be configured tothreadedly engage with threaded portions of the first and second arms506, 508 of the head portion 502. In other embodiments, the securingmember may interlock or otherwise engage the first and second arms 506,508 of the head portion 502 in any other desired fashion in order tocapture a component in the channel 510 of the head portion 502.

A bushing 520 may be configured to be disposed in the channel 510 of thehead portion 502. The bushing 520 may include a first flared end 524, asecond flared end 526 and a medial portion 528 between the first flaredend 524 and the second flared end 526. The bushing 520 may include acentral aperture 522 extending through the bushing 520 from the firstflared end 524 to the second flared end 526. The bushing 520 may beconfigured such that the medial portion 528 is positionable in thechannel 510 of the head portion 502 while the first flared end 524 islocated exterior of the head portion 502 and facing a first side of thehead portion 502 and the second flared end 526 is located exterior ofthe head portion 502 and facing a second side of the head portion 502opposite the first side.

The bushing 520 may be configured such that the connection member 32 mayextend through the aperture 522, allowing longitudinal displacement ofthe connection member 32 through the bushing 420. Thus, when the bushing520 is secured in the head portion 502 of the vertebral anchor 500 withthe set screw 530 or other securing member, the connection member 42(which passes through the aperture 522) may be captured in the channel510 of the head portion 502, yet not be fixedly secured to the headportion 502 of the vertebral anchor 500. This configuration may allowthe connection member 32 to be longitudinally displaceable through thehead portion 502.

Turning now to FIGS. 4-7, a method for installing the vertebral columncorrection system 10 along a portion of a spinal column will now bedescribed. Referring to FIG. 4, a first vertebral anchor 12 can besecured to a first vertebra 18. The first vertebral anchor 12 may have afirst side surface 14 and a second side surface 16. A second vertebralanchor 20 can be secured to a second vertebra 26. The second vertebralanchor 20 may have a first side surface 22 and a second side surface 24.The second vertebra 26 may be positioned adjacent to the first vertebra18 or may be spaced one, two, three, four, or more vertebrae from thefirst vertebra 18. In some embodiments, the vertebral column correctionsystem 10 may further comprise one or more intermediate vertebralanchors 28 disposed between the first and second vertebral anchors 12,20. The one or more intermediate vertebral anchors 28 may be secured toone or more vertebrae 30 between the first and second vertebrae 18, 26.The vertebral anchors 12, 20, 28 may comprise channels, such as throughholes 46 for receiving a connection member 32, such as the pedicle screwillustrated in FIG. 3A. In some embodiments, one or more of thevertebral anchors 12, 20, 28 may be top loading pedicle screws having aU-shaped channel, such as those illustrated in FIGS. 3B-3D, forreceiving the connection member 32 therethrough. The vertebral anchors12, 20, 28 may further comprise a bore 48, or other opening, extendingfrom a top surface of the vertebral anchors 12, 20, 28 for receiving aset screw or other locking means 50. Vertebral anchors, such as thoseillustrated in FIGS. 3B-3D may include a mechanism to provisionally holdthe connection member 32 within the channel as a multi-level constructis assembled.

Referring now to FIGS. 5-6, once the vertebral anchors 12, 20, 28 aresecured in the vertebrae 18, 26, 30, the connection member 32 may beadvanced longitudinally through the channels, such as through holes 46,of the vertebral anchors 12, 20, 28. In some embodiments, the ferruleflange 36 may be attached to the first end 42 of the connection member32 prior to advancing the connection member 32 through the through holes46, or other channels. In this embodiment, the tensioning member 34,shown as the spring member 35, may be disposed over the connectionmember 32 prior to advancing the connection member 32 through thethrough holes 46, or other channels. In some embodiments, the ferruleflange 36 may be secured to the connection member 32 prior to theplacement of the tensioning member 34 (e.g., the spring member 35) andthe tensioning member 34 may be placed over the second end 44 of theconnection member 32 and advanced towards the first end 42 of theconnection member 32 and the ferrule flange 36.

In other embodiments, the tensioning member 34 may be disposed over theconnection member 32 prior to securing the ferrule flange 36 to thefirst end 42 of the connection member 32. In this particular embodiment,the tensioning member 34 may be advanced over either end 42, 44 of theconnection member 32 and positioned adjacent the first end 42 prior toadvancing the connection member 32 through the through holes 46, orother channels.

In other embodiments, the connection member 32 may be advanced throughsome of the vertebral anchors 12, 20, 28 or all of the vertebral anchors12, 20, 28 prior to disposing the tensioning member 34 over theconnection member 32. In this particular embodiment, the second end 44of the connection member 32 may be advanced through any number ofvertebral anchors 12, 20, 28 and the tensioning member 34 may be placedover the first end 42 of the connection member 32. The ferrule flange 36may then be secured to the first end 42 of the connection member 32after the tensioning member 34 has been positioned. The second end 44 ofthe connection member 32 may be advanced through the through hole 46, orother channel, of the first vertebral anchor 12 and then longitudinallyadvanced through the through hole 46, or other channel, of eachintermediate vertebral anchor 28 towards the second vertebral anchor 20.

Referring now to FIG. 7, once the second end 44 of the connection member32 is advanced through the through hole 46, or other channel, of thesecond vertebral anchor 20, tension may be placed on the connectionmember 32 by further pulling the connection member 32 in the directionthe arrow in FIG. 7 away from the spring member 35, or other tensioningmember. As can be seen in FIG. 7, the spring member 35 has a first end38 abutting the ferrule flange 36 and a second end 40 abutting the firstside 14 of the first vertebral anchor 12. As the connection member 32 istensioned, the spring member 35, or other tensioning member, may becompressed and thus shortened from a first length to a shorter secondlength, putting the spring member 35, or other tensioning member, incompression. In some embodiments, the spring member 35 may be a helicalcoil. The coil windings of a helical coil may become closer togetherwhen the spring member 35 is under compression. The tensioning of theconnection member 32 may be done with or without a tensioning tower orother tensioning instrument. The connection member 32 may be tensionedto a prescribed tension and/or adequate correction of the deformity. Thecompression in the tensioning member 34 may maintain a desired amount oftension in the connection member 32. Once the proper amount of tensionis placed on the connection member 32, a set screw 50, or other lockingmeans, may be placed in the bore 48, or other opening, of the secondvertebral anchor 20 to fixedly secure the second end 44 of theconnection member 32 to the head portion of the second vertebral anchor20. The intermediate vertebral anchors 28 may or may not have a setscrew 50, or other locking means to secure the connection member 32 tothe vertebral anchor. Based on the treatment required, set screws 50 orother locking means may be used to secure the connection member 32 withone or more of the intermediate vertebral anchors 28. In embodimentsthat do not use a set screw 50 or other locking means at one or more ofthe intermediate vertebral anchors 28, this may allow for longitudinaldisplacement of the connection member 32 through the head portion of theintermediate vertebral anchors 28 while the connection member 32 iscaptured in the head portions of the intermediate vertebral anchors 28.

In some embodiments, one or more of the intermediate vertebral anchors28 may be one of the vertebral anchors shown in FIGS. 3B-3D, whichcapture the connection member 32 in the head portions without fixedlysecuring the connection member 32 to the head portions. However, in someembodiments, a set screw 50 may be used to secure the connection member32 at an intermediate vertebral anchor 28, if desired. It iscontemplated that the connection member 32 may be secured at any one ormore of the vertebral anchors 12, 20, 28. The set screw 50 may lock theconnection member 32 in place and help maintain the proper amount oftension. If there is excess length of connection member 32 present, theconnection member 32 may be trimmed before or after tensioning. Thetension on the connection member 32 by the spring member 35 or othertensioning member, may be further adjustable by a screw mechanism orother tension adjustment mechanism to attain a desired amount of tensionin the connection member 32. In some embodiments, compression of thetensioning member 34 (e.g., the spring member 35), and thus tension ofthe connection member 32 may be adjusted post operatively and/orpercutaneously to maintain and/or adjust the tension of the connectionmember 32. The tension in the connection member 32 may provide acorrective force to the spinal column to correct a deformity to thespinal column.

Referring now to FIG. 8, an alternative embodiment of a vertebral columncorrection system 410 will now be described. The vertebral columncorrection system 410 may have a first end portion 411 and a second endportion 413. The vertebral column correction system 410 may comprise afirst vertebral anchor 412 secured to a first vertebra 414. A secondvertebral anchor 416 may be secured to second vertebra 418. In someembodiments, the second vertebra 418 may be positioned adjacent to thefirst vertebra 414 or in other embodiments, it may be spaced one, two,three, four, or more vertebrae from the first vertebra 414. In someembodiments, the vertebral column correction system 410 may furthercomprise one or more intermediate vertebral anchors 420 disposed betweenthe first and second vertebral anchors 412, 416. Each of the one or moreintermediate vertebral anchors 420 may each be secured to a vertebra 422between the first and second vertebrae 414, 418. The vertebral anchors412, 416, 420 may comprise channels, such as through holes 424, forreceiving a connection member 430 (e.g., a flexible cord or otherflexible member) such as the pedicle screw illustrated in FIG. 3A. Insome embodiments, one or more of the vertebral anchors 412, 416, 420 maybe top loading pedicle screws having a U-shaped channel, such as thoseillustrated in FIGS. 3B-3D, for receiving the connection member 430therethrough. The vertebral anchors 412, 416, 420 may further comprise abore 426, or other opening, extending from a top surface of thevertebral anchors 412, 416, 420 for receiving a set screw or otherlocking means 428.

The vertebral column correction system 410 may be free of any structurethat constrains the displacement of the head portion of the firstvertebral anchor 412 towards the head portion of each of theintermediate vertebral anchors 420. Similarly, the vertebral columncorrection system 410 may be free of any structure that constrains thedisplacement of the head portion of the second vertebral anchor 416towards the head portion of each of the intermediate vertebral anchors420. In some embodiments, the vertebral column correction system 410 mayalso be free of any structure that constrains the displacement of thehead portion of the intermediate vertebral anchors 420 toward oneanother. For instance, the vertebral column correction system 410 maynot include spacers or other structure disposed around the connectionmember 430 between the head portion of adjacent vertebral anchors 412,416, 420.

Once the vertebral anchors 412, 416, 420 are secured to the vertebrae414, 418, 422, the connection member 430, such as a flexible cord orother flexible member, may be advanced through the channels, such as thethrough holes 424, of the vertebral anchors 412, 416, 420. A first end432 of connection member 430 may be positioned within the channel orthrough hole 424 of the first vertebral anchor 412. A set screw 428, orother locking means, may be positioned within the bore 426 of the firstvertebral anchor 412 to fixedly secure the connection member 430 to thehead portion of the first vertebral anchor 412. A second end 434 of theconnection member 430 may be longitudinally advanced through the channelor through hole 424 of each intermediate vertebral anchor 420 towardsthe second vertebral anchor 416. The second end 434 of the connectionmember 430 may be advanced through the channel or through hole 424 ofthe second vertebral anchor 416. With the connection member 430 securedat the first end portion 411 of the vertebral column correction system410, tension may be placed on the connection member 430 from the secondend 413 of the vertebral column correction system 410. The tensioning ofthe connection member 430 may be done with or without a tensioning toweror other tensioning instrument. The connection member 430 may betensioned to a prescribed tension and/or adequate correction of thedeformity. Once the proper amount of tension is placed on the connectionmember 430, a set screw 428, or other locking means, may be placed inthe bore 426 of the second vertebral anchor 416, fixedly securing theconnection member 430 to the head portion of the second vertebral anchor416. The connection member 430 may be captured in the head portion ofthe intermediate vertebral anchors 420 yet not be fixedly securedthereto, which may allow for longitudinal displacement of the connectionmember 430 through the head portion of the intermediate vertebralanchor(s) 420. However, in some embodiments, a set screw 426, or otherlocking means, may be used to secure the connection member 430 at anintermediate vertebral anchor 420. It is contemplated that theconnection member 430 may be secured at any one or more of the vertebralanchors 412, 416, 420. The set screw 428 may lock the connection member430 in place and help maintain the proper amount of tension. If there isexcess length of the connection member 430 present at the second end 413of the vertebral column correction system 10, the connection member 430may be trimmed before or after tensioning.

The placement of the vertebral column correction systems disclosedherein may depend on the type of deformity to be corrected and/or thecurvature of the spinal column to be corrected. The vertebral columncorrection systems described herein may be particularly advantageous forcorrecting abnormal curvatures caused by scoliosis. The vertebral columncorrection systems, through the tension of the connecting member, mayexert a restoring force on the vertebrae to move the vertebrae into ortoward alignment along the sagittal plane, for example.

Generally, the vertebral column correction system may be secured to theconvex side of a curvature of the spinal column in order to realign thespinal column to a straighter or less curved condition by applying arestoring force to the convex side of the abnormal curvature. Thevertebral column correction system may be implanted anteriorly,posteriorly, anterolaterally, posterolaterally, or laterally, such thatthe vertebral column correction system may be secured to an anterior,posterior, anterolateral, posterolateral and/or lateral aspect ofvertebrae of the spinal column.

The position of the vertebral anchors and/or other components of thevertebral column correction systems may be dictated by the curvature ofthe spinal column on a case by case basis. In some instances, thelocation of the vertebral column correction system may vary from onevertebra to the next vertebra. For example, the position of a vertebralanchor secured to a first vertebra may be different from the position ofa vertebral anchor secured to a second vertebra. Thus, in someinstances, the vertebral column correction system may be implanted in afluctuating arrangement from one vertebra to adjacent vertebra of aspinal column. Thus, the vertebral column correction system may followthe outermost aspect of curvature of the spinal column. In instances inwhich the spinal column has a compound curvature (e.g., has multiplecurved portions), it may be desirable to install the vertebral columncorrection system on the convex sides of each of the curved portions ofthe spinal column.

A single vertebral column correction system may be installed on thespinal column, or multiple vertebral column correction systems may beinstalled on the spinal column, depending on the spinal deformity and/orcorrection desired. For instance, multiple vertebral column correctionsystems, or components thereof, may be installed in parallel on a singleaspect of the spinal column and/or multiple vertebral column correctionsystems, or components thereof, may be installed at different locationsof the spinal column (e.g. throughout different curved regions of thespine). For instance, a plurality of connection members and/ortensioning members may be used in a vertebral column correction systemin order to achieve a desired result. In some instances, a singlevertebral column correction system may be installed unilaterally (i.e.,on a single side), while in other instances multiple vertebral columncorrection systems may be installed multi-laterally (i.e., on multiplesides). For instance, a first spinal column correction system may beinstalled along one side of the spinal column, while a second oradditional spinal column correction system may be installed along asecond side of the spinal column.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departure in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

What is claimed is:
 1. A method of correcting a spinal deformity of aspinal column, comprising: during a first medical procedure: a) securinga first vertebral anchor of a spinal correction system to a firstvertebra on a convex side of an abnormal curvature of the spinal column,the first vertebral anchor including a head portion; b) securing asecond vertebral anchor of the spinal correction system to a secondvertebra on the convex side of the abnormal curvature of the spinalcolumn, the second vertebral anchor including a head portion; c)securing one or more intermediate vertebral anchors of the spinalcorrection system to one or more intermediate vertebra located betweenthe first vertebra and the second vertebra on the convex side of theabnormal curvature of the spinal column, each of the one or moreintermediate vertebral anchors including a head portion; d) capturing aflexible connection member of the spinal correction system within thehead portions of each of the one or more intermediate vertebral anchorswhile maintaining longitudinal movement of the flexible connectionmember through the head portions of at least one of the one or moreintermediate vertebral anchors; and e) tensioning the flexibleconnection member to a first amount of tension between the firstvertebral anchor and the second vertebral anchor to apply a correctionalforce to the convex side of the abnormal curvature to restore the spinalcolumn to a straighter condition; and during a second medical procedure:a) re-tensioning the flexible connection member to a second amount oftension between the first vertebral anchor and the second vertebralanchor to apply a further correctional force to the convex side of theabnormal curvature to restore the spinal column to a straightercondition wherein the spinal correction system allows for displacementof the head portion of the first vertebral anchor toward the headportion of each of the one or more intermediate vertebral anchors. 2.The method of claim 1, wherein a first end of the flexible connectionmember is fixedly secured to the first vertebral anchor during the firstmedical procedure.
 3. The method of claim 2, wherein a second end of theflexible connection member is fixedly secured to the second vertebralanchor during the first medical procedure.
 4. The method of claim 3,wherein the spinal correction system is configured to allow longitudinaldisplacement of the flexible connection member through the head portionof each of the one or more intermediate vertebral anchors between thefirst medical procedure and the second medical procedure.
 5. The methodof claim 1, further comprising: during the first medical procedure:coupling a tensioning member to a first end of the flexible connectionmember, wherein the tensioning member maintains the first amount oftension in the flexible connection member.
 6. The method of claim 5,wherein the tensioning member is compressed from a first length to asecond length when the flexible connection member is tensioned to thefirst amount of tension.
 7. The method of claim 1, wherein the spinalcorrection system is free of structure that constrains the displacementof the head portion of the second vertebral anchor toward the headportion of each of the one or more intermediate vertebral anchors.
 8. Amethod of correcting an abnormal curvature of a spina column,comprising: creating post-operatively an open access to a previouslyimplanted spinal column correction system, said previously implantedspinal column correction system having a first tension applied to aflexible cord disposed between a first vertebral anchor attached to afirst vertebra on a convex side of the abnormal curvature of the spinalcolumn and a second vertebral anchor attached to a second vertebra onthe convex side of the abnormal curvature of the spinal column; whereinthe flexible cord is connected between the first vertebral anchor andthe second vertebral anchor such that the flexible cord extends througha head portion of one or more intermediate vertebral anchors attached toone or more intermediate vertebra located between the first vertebra andthe second vertebra on the convex side of the abnormal curvature of thespinal column; and re-tensioning the flexible cord to a second amount oftension between the first vertebral anchor and the second vertebralanchor to apply a correctional force to the convex side of the abnormalcurvature to restore the spinal column to a straighter condition whereinthe previously implanted spinal correction system is free of structurethat constrains the displacement of the head portion of the firstvertebral anchor toward the head portion of each of the one or moreintermediate vertebral anchors.
 9. The method of claim 8, wherein thepreviously implanted spinal column correction system is free ofstructure that constrains the displacement of the head portion of thesecond vertebral anchor toward the head portion of each of the one ormore intermediate vertebral anchors.
 10. A method of correcting anabnormal curvature of a spinal column, comprising: creatingpost-operatively an open access to a previously implanted spinal columncorrection system, said previously implanted spinal column correctionsystem having a first tension applied to a flexible connection memberdisposed between a first vertebral anchor attached to a lateral aspectof a first vertebra of a spinal column and a second vertebral anchorattached to a lateral aspect of a second vertebra of the spinal column;wherein the flexible connection member is connected to the firstvertebral anchor and to the second vertebral anchor defining a portionof the flexible connection member therebetween such that the flexiblecord extends through a head portion of one or more additional vertebralanchors attached to one or more intermediate vertebra located betweenthe first vertebra and the second vertebra; adjusting the first tensionapplied to the flexible connection member between the first vertebralanchor and the second vertebral anchor to a second tension differentfrom the first tension; wherein the second tension applied to theconnection member is effective to apply a correctional force to a convexside of the abnormal curvature to restore the spinal column to astraighter condition; and closing the open access to the previouslyimplanted spinal column correction system wherein the spinal correctionsystem allows for displacement of a head portion of the first vertebralanchor toward the head portion of each of the one or more intermediatevertebral anchors.
 11. The method of claim 10, wherein the one or moreadditional vertebral anchors each of which is attached to its ownvertebra of the spinal column located between the first vertebra and thesecond vertebra.
 12. The method of claim 11, wherein the one or moreadditional vertebral anchors of the previously implanted spinal columncorrection system each include an aperture through which the flexibleconnection member passes.
 13. The method of claim 12, wherein theflexible connection member passes freely through each aperture of theone or more additional vertebral anchors each of which is attached toits own vertebra of the spinal column located between the first vertebraand the second vertebra.
 14. The method of claim 13, wherein thepreviously implanted spinal column correction system includes atensioning member which is adjustable to adjust the flexible connectionmember to the second tension.
 15. The method of claim 10, wherein thefirst tension is less than the second tension.
 16. The method of claim10, wherein the second tension increases the first tension to maintainan initial tension of the previously implanted spinal column correctionsystem.
 17. The method of claim 10, wherein the first tension is greaterthan the second tension.